The state Legislature advanced the bill that would create a quake warning system during Thursday's last hours of its session. Gov Jerry Brown has until Oct 13 to decide.
The US lags behind other nations in developing a public alert system, which provides several seconds of warning after a fault ruptures enough time for trains to brake, utilities to shut off gas lines or people to dive under a table until the shaking stops.
The biggest challenge is finding steady funding to support and maintain a statewide network. The bill does not address where funding to create the alert system would come from, but it can't be built using general fund revenues. State emergency managers would have until 2016 to hash out the funding, estimated at USD 80 million for the first five years of operation.
Seismic early warning systems are designed to detect the first shock waves from a large jolt, calculate the strength and alert people before the slower but damaging waves spread.
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During the 2011 Japanese disaster, millions of people received 5 to 40 seconds of warning depending on how far they were from the epicenter. The notices were sent to cellphones and broadcast over airwaves.
"This is doable" in California, said USGS seismologist Doug Given, who heads the testing.
Before launching a quake alert system, scientists would need to upgrade old monitoring stations and add an extra 440 seismic sensors in vulnerable regions such as the northern tip of the San Andreas near San Francisco and the San Jacinto Fault in Southern California.